Under the award from Brazil's Embraer Defense and Security, R&S will deliver its M3AR software-defined VHF/UHF airborne transceiver, which features encryption and frequency-hopping capabilities.
The first units will be delivered by next year for KC-390 development prototypes, K&S said.
Brazil's Embraer is developing the medium-lift aircraft specifically for the country's air force, which plans a fleet of 28 KC-390s. Embraer also plans to build an additional 32 of the planes for use by regional customers.
Each aircraft will be outfitted with two VHF/UHF transceivers.
R&S didn't disclose the value of the contract but said that with the order more than 6,000 of its M3AR units have been sold to customers around the world.
The M3AR is in use on aircraft such as the A400M by Airbus Military, the Eurofighter and the F-16.